1. Field Of The Invention.
The present invention relates to an inflatable cushion assembly for incorporation in an inflatable restraint system.
2. Related Art.
Inflatable restraint systems generally include an inflatable cushion, commonly referred to as an air bag and hereinafter referred to as a cushion, disposed within a housing, and an inflator for generating a fluid, usually in the form of a gas, for inflating the cushion. The cushion is typically formed of a flexible material such as nylon, and stored within the housing in a folded or collapsed condition. The cushion has a gas inlet opening which is attached to the housing and/or inflator to permit entry of the gas into the cushion after being activated by the inflator. The gas is directed from the inflator into the cushion by means of a diffuser containing a plurality of orifices for distributing the gas into the cushion in a substantially uniform manner. The diffuser therefore serves the function of throttling the flow of gas and provides for the proper fill rate to the cushion. The presence of a diffuser somewhat reduces the possibility of rupture of the cushion, or separation from its attachment within the system, owing to the effects of heat and pressure from the inflator gas during the cushion's deployment.
Attachment of the cushion to its associated counterpart within an inflatable restraint system is therefore important for the successful deployment of the cushion and safe operation of the system. Various types of designs have been used in the past. One such design is disclosed in U.S. Pat. No. 5,141,247 issued to Barth, wherein an air bag, inflator and support plate are clamped together using a series of tabs extending from a circular retainer member. One set of tabs extend radially outward from the retainer member to clamp the air bag between the support plate and the retainer flange, while another series of tabs are used to clamp the inflator flange and support plate together. The retainer member therefore secures the air bag, inflator and support plate together. Unfortunately, the addition of another part to the module adds to the complexity of the system thereby adding weight and cost of materials for the assembly and production of the air bag module.
U.S. Pat. No. 5,226,671 issued to Hill discloses deflectable flaps formed at the fluid inlet opening of an air bag by providing a series of slits at the inlet opening. However, the flaps overlie the fluid inlet opening of the air bag and are not used to secure the air bag to the housing. Securement is accomplished by a series of mounting holes in the cushion located radially outward of the deflectable flaps.
Another system for incorporating an air bag into an inflatable restraint system is described in U.S. Pat. No. 5,240,282 issued to Wehner et al. which shows a pair of end flaps 40a and 40b fastened to a housing by a series of studs inserted into openings provided in the flaps. The system, however, utilizes a retainer member for the combined attachment of the inflator and air bag within the housing.
And in U.S. Pat. No. 5,261,963 issued to Krickl et al., the border of the inlet opening of the air bag is connected to a housing by the use of rods inserted into tubular portions formed at the inlet opening which in turn are inserted into corresponding grooves of a quadrangular base plate for securing the bag to the housing.
In each of the foregoing patents, the attachment of the cushion is complicated in that extra materials are needed in the form of retention plates, frames or rods. The mounting structures are such that the gas inlet opening of the cushion is susceptible to rupture or tearing from its associated housing during the deployment process. Moreover, as inflatable restraint systems become more compact, less room is available for the individual components that make up the air bag module which requires that the attachment assembly for the cushion be efficient in overall design. The design of the cushion assembly must also be such that the cushion, especially at its gas inlet opening, is protected from the heat and fragments of the inflator gas when the inflator is activated.